Dedicated feedback channels have been introduced to improve performance for multicast services and broadcast services, such as Enhanced Multicast and Broadcast Services (E-MBS) for 802.16m and evolved Multicast Broadcast Multimedia Systems (eMBMS) for 3rd Generation Partnership Project (3GPP) High Speed Packet Access (HSPA) and Long Term Evolution (LTE) and to allow the service provider to determine, for example, transmission parameters for various services, including for example, broadcast services.
For dedicated feedback channels, each WTRU may be assigned its own resources for feedback. While it may be possible to reduce WTRU battery consumption by, for example, only transmitting negative acknowledgements, the resources cannot be used for other WTRUs. Moreover, while this method allows the base station to know the exact identity of the WTRU, providing feedback for a large number of WTRUs requires a prohibitive amount of uplink resources.